Bladder fuel pump



April 20, 1965 D. N. ARNDT ETAL 3,179,054

BLADDER FUEL PUMP Filed July 23, 1962 [NGl/VE United States Patent 3,179,054 BLADDER FUEL PUMP Donald N. Arndt, Charles H. Tuckey, and J. D. Tuckey, Cass City, Mich., assignors to Walbro Corporation, Cass City, Mich, a corporation of Michigan Filed July 23, 1962, Ser. No. 211,600 8 Claims. (Cl. 103-44) This invention relates to a bladder fuel pump and is directed to the creation of a small, simple fuel pump for small engines.

In the use of small engines for chain saws and other small appliances, frequently it is necessary to tip the engines to various angles even to the extent of complete inversion. Thus, with a gas tank below the carburetor, an engine will soon stop unless means is provided to supply fuel to the carburetor. Also in the design of non-invertable engines it still may be desirable to place the fuel supply below the carburetor for design reasons relating to cost and appearance.

With cost a vital factor in the design of these engines in what is now a highly competitive industry, it has become a problem to provide a simple and effective pump to move fuel up into a carburetor from a fuel supply.

The present invention is a result of this problem and has for its object a simple design, inexpensive, and eflicient.

Another object of the invention is the provision of a versatile booster arrangement which makes the pump adaptable for use on both two-cycle and four-cycle engines. It has been discovered that in four-cycle actuation, the suction rating is greater than the positive pressure in the pulse, whereas in a two-cycle engine the pulsation to the pump is more of a positive pressure and less of suction. A smooth pumping action can he obtained by a supplemental force applied to the diaphragm in the direction of the lesser pulsation. To adapt the pump, therefore, to both types of engines, it is proposed to provide a diaphragm which is reversable in the pump housing and a spring means which can be applied on one side of the diaphragm for one type of engine and on the other side of the diaphragm for another type of engine. Thus, the same pump can be most efiiciently adapted to use on either engine.

Another feature of the present invention is the use of a simple supplemental sump chamber which receives fuel as a result of the inertia of the fuel flow after the completion of a particular stroke of the diaphragm.

This provides a ready supply of fuel for the return stroke 'ofthe diaphragm and results in a more continuous pumping supply, the entire combination increasing the capacity of the pump materially.

Another feature of the invention is the detail of the supplemental or sump housing which allows it to be adapted to a regular pump housing when desired, together with a simple filter which is held in place by the assembly of the parts.

Other objects and features of the invention relating to details of construction and operation will be apparent in the following description and claims.

Drawings accompany the disclosure and the various views thereof may be briefly described as:

FIGURE 1, a sectional view of the pumping assembly showing the relationship of the parts.

FIGURE 2, a modified assembly adapted for another type of engine.

FIGURE 3, a view of a pump without the supplemental sump chamber.

Referring to the drawings:

In FIGURE 1 a pump housing 20 joined with a snapice on cap 22 forms a pumping chamber 24 defined at one end by a diaphragm 26. On the cap side of the diaphragm 26 is a pulsation chamber 28, the cap having a projection 30 for connection with the crankcase or manifold of an engine. The upper edge of the housing 20 has a bead 32 which serves as a retainer for a snap-over head 34 on the annular edge of the cap 22. The housing 20 and the cap 22 have mating annular surfaces which confine the annular outside edges of the diaphragm 26. This diaphragm has a flat reinforcing disc 36 on one side and a spring seat reinforcing disc 38 on the other side having a central raised portion to serve as a locator and spring seat.

In FIGURE 1 a spring 40 bears at one end on the spring seat 38 and at the other end on the inner wall of the cap 22. The housing 20 has an inlet opening 42 terminating in a unidirectional valve 44 which consists essentially of a disc 46 and a frictionally-seated, skeletal retainer 48. The opening 42 is in a depending cylindrical projection 50 at the bottom of the housing 20. The housing 20 has an outlet passage 52 including a uni directional outlet valve 54 in a suitable outwardly extending projection 56 which can be connected directly to a carburetor or supply tube. The projection 58 on the opposite side of the housing 20 is for purposes of the application of a wrench to the housing.

In FIGURE 2, the identical structure is shown except that the diaphragm 26 is inverted so that the spring seat 38 is on the lower side cooperating with a spring 60 seated at one end on seat 38 and at the other end in an annular groove 62 in the bottom wall of chamber 24.

In both FIGURES l and 2, a supplemental sump chamber 70 is formed by a cup-shaped housing 72 preferably formed of a plastic material of the same type as could be used for the cap 22. A small annular bead 74 at the base of the housing 20 retains the housing 72 through an internal groove 76 which interlocks with the bead. The housing 72 has a projection 78 for the attachment of a fuel supply hose with an inlet opening 80 which is fairly near the top of the chamber 70. The inlet opening 42 at the bottom of the housing 20 is fairly near the bottom of the sump chamber 70. A shoulder 82 on the inside wall of housing 72 is positioned axially adjacent a shoulder 84 on the outer surface of the projection 50. This permits a positioning of an annular filter element 86 between these spaced shoulders in -a simple and convient way.

In the operation of the device, it has been previously stated that the pump is adapted to be used with both a four-cycle engine and a two-cycle engine to assist the weaker of the pulsations operating the diaphragm. In a four-cycle engine, the pulsations taken from the intake passageway have considerably more suction than push. For example, the suction might be a negative 6 inches of mercury, whereas the pressure phase is 2 inches of mercury. In order to balance the stroke of the pump, a device such as shown in FIGURE 1 can be used wherein on the high suction stroke the spring 40 is compressed and on the lower positive pressure stroke, the spring 40 supplements the pressure, the object being to get a balanced stroke in each direction.

In a two-cycle engine, the positive pressure in the crank case is much higher than the suction. Consequently, as shown in FIGURE 2, a spring 60 is placed beneath the inverted diaphragm so that the positive pressure in the pressure inlet 30 can compress the spring 60 allowing it to assist the weaker suction stroke again to balance the pulsations. In addition, this construction cooperates with the supplemental chamber 70 since fluid may accumulate in this chamber, for example, following the upstroke of the diaphragm. With the small pump of this nature, the fuel being moved in from the fuel supply 3 in a rising column, for example, will continue to move after the valve 44 has closed. The reduced pressure in chamber 76, resulting from the upstroke of the diaphragm, will permit the rising column to move into the supplement sump chamber, thus assuring an immediate response when the valve 4-4 again opens in response to v the rising motion of the diaphragm. In an actual commercial structure, this device comprises a body with about 1%" overall height With a 2" overall height, including the supplemental chamber. Thus, this extremely small pump can produce efficiently under varying circumstances and can pump suificient quantity to supply an'internal combustion engine for such uses as chain saws, lawn mower drives, go-carts, etc.

In FIGURE 3, a simplified version of the pump without the supplemental chamber is shown, this device again being adaptable to utilizing a spring above the diaphragm or below if desired.

We claim:

1. A fuel pump for small engines to operate from a source of pulsating pressure in the engine of the type including:

(a) a main housing forming a pumping chamber having inlet and outlet openings,

(b) an inlet valve and an outlet valve in said respective openings, said housing having an opening for receiving pulsating pressure,

() a diaphragm separating said pressure opening from the inlet and outlet openings,

(d) a separable supplemental housing forming, in conjunction with the outside of said main housing, a supply chamber connected to said inlet,

(e) means for supplying fuel to said supply chamber having a supply opening above the bottom of said supply chamber,

(f) a connection to the inlet of said pumping chamber having an opening in said supply chamber adjacent the bottom thereof and below the supply opening,

(g) an annular shoulder on the inner wall of said supplemental housing,

(h) a projection on said main housing forming an inlet opening, said projection having an annular shoulder, and

(i) an annular filter element located on its Outer periphery by the shoulder on said supplemental housing wall and on its inner surface by the shoulder on said projection wherein it is interposed between said supply opening and said inlet opening.

2. The fuel pump set forth in claim 1 wherein said supplemental housing is formed of semi-resilient material in the shape of a cup having a month, said main housing and said supplemental housing being telescopically engaged, a groove on one of said housings, a head on the other of said housings registering with said groove when said housings are telescopically engaged to lock said housings together.

3. The fuel pump set forth in claim 1 wherein said fuel supplying means for said supply chamber comprises a fitting on said supplemental housing, said fitting and said supplemental housing having a passageway therethrough communicating between said supply chamber and the exterior of said housing.

4. In the method of assembling a fuel pump selectively usable with either a two-cycle engine or a four-cycle engine and operated by pressure pulsations therefrom, said pump being of the type having a walled chamber defined by a housing which has separable portions with mating surfaces, one of said portions being formed of semi-resilient material, one of said portions having an annular bead thereon, the other of said portions having an annular groove that mates with said bead to provide a separable snap-together connection between said portions, a diaphragm detachably mounted within said walled chamber and confined at its margin by said mating surfaces to divide said walled chamber into a pulsating portion and a pumping portion, said pulsating portion having an inlet for connection to said engine, said pumping portion having an inlet and an outlet with respective inlet and outlet valve means, means on said diaphragm to serve as a spring seat, and a spring having one end engaging said spring seat and the other end engaging a wall of said chamber, the steps of selectively mounting said diaphragm with said spring positioned in said pulsating portion for selected use of said pump with said four-cycle engine and said spring positioned in said pumping portion for selected use of said pump with said twocycle engine, and then confining said diaphragm at its margin between said mating surfaces.

5. A fuel pump selectively usable with either a twocycle engine or a four-cycle engine and operated by pressure pulsations therefrom comprising:

(a) a walled chamber defined by a housing having separable portions with mating surfaces,

(1)) a diaphragm detachably mounted Within said walled chamber and confined at its margin by said mating surfaces to divide said walled chamber into a pulsating portion and a pumping portion, said pulsating portion having an inlet for connection to said engine, said pumping portion having an inlet and an outlet with respective inlet and outlet valve means,

(0) means on said diaphragm to serve as a spring seat,

(d) a spring having one end engaging said spring seat and the other end engaging a wall of said chamber, said diaphragm being selectively mounted in said walled chamber with said spring selectively positioned in one of saidportions for selected use of said pump with one of said engines and selectively mounted in said chamber with said spring selectively positioned in the other of said portions for selected use of said pump with the other of said engines,

(2) a separable supplemental housing forming, in conjunction with the outside of said main housing, a supply chamber connected to said inlet,

(f) means for supplying fuel to said supply chamber having a supply opening above the bottom of said supply chamber,

(g) means forming a connection to the inlet of said pumping chamber having an opening in said supply chamber adjacent the bottom thereof and below the supply opening,

(h) an annular shoulder on the inner wall of said supply chamber,

(i) a projection on said main housing forming an inlet opening, said projection having an annular shoulder, and

(i) an annular filter element located on its outer periphery by the shoulder on said supply chamber wall and on its inner surface by the shoulder on said projection wherein it is interposed between said supply opening and said inlet opening.

6. A fuel pump selectively usable with either a twocycle engine or a four-cycle engine and operated by pressure pulsations therefrom comprising:

(a) a Walled chamber defined by a housing having separable portions with mating surfaces, one of said portions being formed of semi-resilient material, one of said portions having an annular bead thereon, the other of said portions having an annular groove that mates with said head to provide a separable snap-together connection between said portions,

(b) a diaphragm detachably mounted within said Walled chamber and confined at its margin by said mating surfaces to divide said walled chamber into a pulsating portion and a pumping portion, said pulsating portion having an inlet for connection to said engine, said pumping portion having an inlet and an outlet with respective inlet and outlet valve means,

(c) means on said diaphragm to serve as a spring seat,

and

(d) a compression spring having one end bearing against said seat, the other end bearing against a wall of said chamber, said diaphragm being selectively mounted in said chamber with said spring selectively positioned in said pulsating portion for selected use of said pump with said four-cycle engine and said spring being selectively positioned in said pumping portion for selected use of said pump with said two-cycle engine.

7. A fuel pump for small engines operable from pulsating pressure in the engine comprising:

(a) a walled chamber defined by a housing, said housing having two separable portions with mating annular faces, one of said portions being formed of semi-resilient material, one of said portions having an annular bead thereon, the other of said portions having an annular groove that mates with said bead to provide a separable snap-together connection between said portions,

(1;) a diaphragm detachably mounted within said walled chamber and confined at its margin by said mating faces to divide said walled chamber into a pulsating portion and a pump portion, said pulsating portion having an inlet for connection to said engine, said pump portion having an inlet and an outlet with respective inlet and outlet unidirectional valve means,

(0) a compression spring, and

(d) a spring seat, said spring seat being disposed in said pulsating portion and abutting one side of said diaphragm, said spring having one end engaging said spring seat and the other end engaging a wall of said pulsating portion of said chamber.

8. A fuel pump for small engines operable from pulsating pressure in the engine comprising:

(a) a main housing forming a pump chamber having inlet and outlet openings,

(b) a hollow projection on said main housing communicating with said inlet opening,

(c) a unidirectional inlet valve and a unidirectional outlet valve for controlling fluid flow through said respective openings, said housing having an opening for receiving pulsating pressure from said engine.

(d) a diaphragm separating said pressure opening from said inlet and outlet openings (e) a cup-shaped supplemental housing, said main housing and said supplemental housing being telescopically engaged to form a supply chamber therebetween communicating with said inlet, one of said housings having a semi-resilient portion,

(1) snap-together means, including said semi-resilient portion, on said housings for sealably and frictionally locking said housings together in telescopic relation, and

(g) means for supplying fuel to said supply chamber comprising a projection on said supplemental housing, said projection having a passageway therethrough communicating between said supply chamber and the exterior of said supplemental housing to form an inlet fitting for said supply chamber, said passageway opening into said supply chamber above the bottom thereof, and said main inlet communicating with said supply chamber below the opening of said passageway.

References Cited by the Examiner UNITED STATES PATENTS 2,179,925 11/39 Dilg 103-53 2,298,756 10/42 Erickson 103-150 2,344,287 3/44 Creveling 103150 2,381,594 8/45 Holthouse 10344 2,673,522 3/54 Dickey 103-44 2,984,188 5/61 Tuckey et al 103 -44 LAURENCE V. EFNER, Primary Examiner.

ROBERT M. WALKER, Examiner. 

1. A FUEL PUMP FOR SMALL ENGINES TO OPERATE FROM A SOURCE OF PULSATING PRESSURE IN THE ENGINE OF THE TYPE INCLUDING: (A) A MAIN HOUSING FORMING A PUMPING CHAMBER HAVING INLET AND OUTLET OPENINGS, (B) AN INLET VALVE AND AN OUTLET VALVE IN SAID RESPECTIVE OPENINGS, SAID HOUSING HAVING AN OPENING FOR RECEIVING PULSATING PRESSURE, (C) A DIAPHRAGM SEPARATING SAID PRESSURE OPENING FROM THE INLET AND OUTLET OPENINGS, (D) A SEPARABLE SUPPLEMENTAL HOUSING FORMING, IN CONJUCTION WITH THE OUTSIDE OF SAID MAIN HOUSING, A SUPPLY CHAMBER CONNECTED TO SAID INLET, (E) MEANS FOR SUPPLYING FUEL TO SAID SUPPLY CHAMBER HAVING A SUPPLY OPENING ABOVE THE BOTTOM OF SAID SUPPLY CHAMBER, (F) A CONNECTION TO THE INLET OF SAID PUMPING CHAMBER HAVING AN OPENING IN SAID SUPPLY CHAMBER ADJACENT THE BOTTOM THEREOF AND BELOW THE SUPPLY OPENING, (G) AN ANNULAR SHOUDLER ON THE INNER WALL OF SAID SUPPLEMENTAL HOUSING, (H) A PROJECTING ON SAID MAIN HOUSING FORMING AN INLET OPENING, SAID PROJECTION HAVING AN ANNULAR SHOULDER, AND (I) AN ANNULAR FITLER ELEMENT LOCATED ON ITS OUTER PERIPHERY BY THE SHOULDER ON SAID SUPPLEMENTAL HOUSING WALL AND ON ITS INNER SURFACE BY THE SHOULDER ON SAID PROJECTION WHEREIN IT IS INTERPOSED BETWEEN SAID SUPPLY OPENING AND SAID INLET OPENING. 